Structo wrote:The problem stemmed from a certain amp company in Malaysia that used data from this site to build much of their product line.
I think what was hurtful was that the man never acknowledged this forum or any other credit to individuals that provided information.
Also customers of said amp company would come here for tech support, rather than the forum provided by the manufacturer.
It's just a little niggle.
Ok, I get it. But by blocking one person, everyone else is left in the dark too. Also, it seems the cat's out of the bag already so why keep up the secrecy?
I've spent a lot of time making highly detailed layouts of holy grail amps to share with everyone in the tube community because that's what the tube community does, share. I really don't mind if a Malaysia amp builder grabs up that info and sells clones. In fact, more power to them if they can make a profit at it I sure couldn't. I don't begrudge anyone that opportunity. But what the sharing is all about is helping people who want to build their own amp get it done to spread the tone. But that's just me I guess.
Is the polarity of the presence cap on this schematic correct? I think the positive side should be connected to the pot center wiper and the negative side to ground. Or am I missing something (like reading the schematic wrong)? I think the curved part of a polarized cap indicates negative.
Is the polarity of the presence cap on this schematic correct? I think the positive side should be connected to the pot center wiper and the negative side to ground. Or am I missing something (like reading the schematic wrong)? I think the curved part of a polarized cap indicates negative.
Thanks,
Mike
Yes the schematic is incorrect, the negative goes toward the 380 resistor.
"You feel like you're floating on a football field filled with marshmallows." -Dumble
Looks like on an electrolytic the line is negative. That does look different than #124. It has been almost a decade since I built my #124 so I cant remember anymore if these issues were discussed at some time. http://img.photobucket.com/albums/v670/ ... larity.jpg
You do not have the required permissions to view the files attached to this post.
"You feel like you're floating on a football field filled with marshmallows." -Dumble
I think the correct size HRM board layout was never uploaded. Here it is. Realize when I built this some of the trimmers work in reverse. For my purposes I copied the pictures exactly and that is how it came out . I don't know the original, I only know the pictures, so I won't comment if that is right or wrong.
You do not have the required permissions to view the files attached to this post.
"You feel like you're floating on a football field filled with marshmallows." -Dumble
The first one I made was too short so I just 'stretched' the drawing, I did not spend time to re-do the circles, however, because they are just markers for drill holes and I was anxious to etch the board.
My dimensions were based on the width of my main board that I made and those dimensions were dictated by the holes, already drilled in the chassis I used. So, perhaps no real connection to an original.
I did not realize the size was too big until you pointed it out. I suspect I have printed it out at 50%.
"You feel like you're floating on a football field filled with marshmallows." -Dumble
It has been quite a few years since I opened this. I like using the FET input, but it has started acting up, so time for some diagnostics on the FET circuit to find out what is wrong.
file-2373.jpg
You do not have the required permissions to view the files attached to this post.
"You feel like you're floating on a football field filled with marshmallows." -Dumble
ic-racer wrote: ↑Sat Aug 21, 2021 12:19 pm
It has been quite a few years since I opened this. I like using the FET input, but it has started acting up, so time for some diagnostics on the FET circuit to find out what is wrong.
There has been some new learnings on the FET circuit, captured in the FET bias document located in the D files section.
ic-racer wrote: ↑Sat Aug 21, 2021 12:19 pm
It has been quite a few years since I opened this. I like using the FET input, but it has started acting up, so time for some diagnostics on the FET circuit to find out what is wrong.
There has been some new learnings on the FET circuit, captured in the FET bias document located in the D files section.
Nice to see people still advancing our knowledge of these circuits. I built the FET on this amp and my 124 with the exact same circuit values. This was based on the 124 pictures but without any voltage information.
Since my 124 FET works great, I'm thinking maybe the input jack on this amp has an issue or there is a B+ issue.
Last edited by ic-racer on Sun Aug 22, 2021 12:15 pm, edited 1 time in total.
"You feel like you're floating on a football field filled with marshmallows." -Dumble
I found this yesterday when I searched for recent FET threads. Knowing these voltages is fantastic as I don't recall ever seeing information like that before (but I have been out of the loop for a few years).
Martin,
FET NTE 452
Drain 10k ( top 10.48v/ bottom 3.82v)
Source 3.3k ( 2.182v)
Caps were both the same sized tantalum. So I am assuming 4.7uf
B+ on top of the 150k was 302v(150k/8.2k divider)
All NTE resistors
The FET sounded really good. Strong but still transparent.
CW
Above quoted from this thread: https://ampgarage.com/forum/viewtopic.php?f=4&t=34108
"You feel like you're floating on a football field filled with marshmallows." -Dumble
